نشریه آفات و بیماریهای گیاهی
سال هشتاد و دوم شماره 1 (پیاپی 98، شهریور 1393)

The effect of different artificial diets based on the seeds of one cowpea cultivar (Mashhad) and four chickpea cultivars (Arman, Azad, Binivich and Hashem) on biological and life table parameters of Helicoverpa armigera (Hübner) was studied at 25±1ºC, 65±5% RH and a photoperiod of 16:8 (L:D) hours. The larval period ranged from 13.26 to 21.54 days on Binivich and Mashhad, respectively. The longest and shortest development time of H. armigera was on Hashem (38.62±1.56 days) and Azad 33.81±0.09 days), respectively. The highest fecundity (total number of eggs laid per female) was obtained on Mashhad 1227.23±10.27 eggs) and lowest value of this parameter was on Arman (351.00±1.29 eggs). The highest net reproductive rate (R0) was on Mashhad 250.60 ±0.25 female offspring) and lowest value of this parameter was on Arman (59.49±0.49 female offspring). The intrinsic rate of increase (rm) was the highest on Azad (0.205±0.001 day-1) and lowest on Arman (0.140±0.006 day-1). In different host plants examined, the value of mean generation time (T) ranged from 24.11±0.25 to 30.41±1.30 days and doubling time (DT) ranged from 3.22±0.5 to 4.88±0.25 days. The results indicated that Azad and Arman were the most suitable and unsuitable cultivars incorporated into artificial diet for population growth of H. armigera, respectively.

Due to various economical and health drawbacks of high pesticide residue levels, monitoring them on food stuff is very important. In the greenhouses of Isfahan province various pesticides are being used of which highest consumption and toxicity is of the insecticides, therefore presence of high residue levels on their products is not far from expectation. To trace the residue levels of four insecticides (Dichlorovus, Deltamethrin, Imidacloprid and Pymetrozine) on cucumber, samples were collected every thirty days from the greenhouses of four cities, Falavarjan (4 greenhouses), Esfahan (4 greenhouses), Dehaghan (2 greenhouses) and Shahreza (2 greenhouses) during the cultivation season. A total of 192 samples (combination of greenhouse, Insecticide, City) were collected and analyzed. Samples collected from Isfahan city showed levels of Dichlorovus, Deltamethrin, Imidacloprid and Pymetrozine to be 70, 55, 12 and four times the Maximum Residue Levels (MRLs) respectively. Similarly high levels of Dichlorovus and Imidacloprid were detected on the samples of other cities. Percentages of highly contaminated samples with all four insecticides in different cities were 34, 39, 34 and 46 for Isfahan, Falavarjan, Shahreza and Dehaghan cities respectively. Therefore it is clear that all the cities have about 35-45 percent of their cucumber samples under investigation having insecticide residue levels higher than the MRLs. Overall the results show that in Isfahan, Falavarjan, Shahreza and Dehaghan about 33, 33, 35 and 41 percent of the samples analyzed have higher levels of one or more insecticides checked higher than the MRLs respectively. Therefore consumption of this produce could be a threat to the health of the consumers.

Colorado potato beetle, Leptinotarsa decemlineata (Say), is the most important defoliating pest of potato throughout the world and Iran which considerably reduce crop yield. In this study tolerance of 33 cultivars of potato were compared during 2007-2008 in the field conditions. Experiment was carried out in both years in two trials, infested and non infested plots and arranged based on a randomized complete block design. In infested plots, each plant was infested by 40 medium larvae (second and early third instars) 15 days prior to the blooming of plants. Non-infested plots were kept pest-free by chemical and mechanical control methods. At the end of the season, defoliation and yield loss in infested plots were determined and compared with non-infested plots in each cultivar. Cluster analysis of cultivars was performed with MINITAB15 statistical software using UPGMA procedure based on Euclidean distance. Combined analysis of variance of tolerance data in 2007 and 2008 showed significant differences among the cultivars (P < 0.01). Moreover, for all studied traits reciprocal effect of cultivar × year was significant (P < 0.05). Cluster analysis based on defoliation and yield loss in two experimental years showed that cultivars “Santana”, “Satina”, “Bridjet” and “Cardinal” had the highest tolerance to the Colorado potato beetle. Significant positive correlation was observed between yield loss and defoliation traits in two years of study (P<0.01).

During 2011 and 2012, a total of 932 alfalfa leaf samples with yellows, reddening, necrosis and stunting were collected from Lorestan and Ilam provinces. Samples were tested by tissue blot immuno assay (TBIA) using 5G4 monoclonal antibody (a broad spectrum antibody against wide range of legume infecting luteoviruses) in which 35% of random leaf samples showed positive reaction. Molecular analysis confirmed the infection of samples by Beet western yellows virus-BWYV (Polerovirus genus). Inoculation tests using green peach aphids (Myzus persicae) induced vein clearing in sugar beet cv. IC1, vein yellowing in canola (cultivar Otsubu), stunting in white mustard and severe vein yellowing in alfalfa cv. Hamedani. A DNA fragment with the expected length of 560 bp corresponding to BWYV coat protein (CP) gene was amplified. PCR-RFLP analysis using Sma I also revealed BWYV specific profile for the studied isolates. The identity of BWYV-CP gene was 98.6 to 99.4 %.among the Iranian isolates at nt levels The lowest and highest sequence identities were 92.5 % and 97 % with isolates from Italy (L40020) and FL1 (X13063) from France, respectively. Phylogenetic tree using NJ method showed that Iranian BWYV isolates clustered into two subgroups. This is the first report of BWYV occurrence in alfalfa fields in Iran and their CP nucleotide sequences.

The pistachio red bug, Lygaeus pandurus is one of the most destructive true bugs of pistachio in Kerman province. In order to better understanding about the nutritional physiology of the pest, after dissecting adults under stereomicroscope their midguts and salivary glands were removed. The tissues were homogenized and centrifuged and the supernatants were used as the enzyme source in subsequent experiments. Using specific substrates, carbohydrase activity and some of their characteristics were determined. The optimal pH for activity of a- amylase in the midgut and salivary glands were 5 and 6, respectively. Maximum activity of a- and b- glucosidase were observed at pH 5 in the midgut and at pH 5 and 6, in salivary glands, respectively. Optimal temperature for a-amylase activity in midgut and salivary glands obtained 50 and 40 °C, respectively. Midgut
- and -glucosidase were optimally active at 4 °C and maximum activity of a and b- glucosidase in salivary glands were determined at 30 and 35 °C, respectively. Midgut a amylase activity of this pest decreased in presence of Ca2+, Mg2+ and EDTA. Midgut
-glucosidase activity was highest in the presence of Ca2+. In contrast, Mg2+ increased midgut b-glucosidase activity. Zymogram analysis showed one form of a-glucosidase and one form of b glucosidase in both midgut and salivary glands of this pest. Two isoforms of a-amylase were detected in salivary glands and three isoforms of a amylase in midgut of this pest.

Fusarium culmorum, is one of the most important causal agents of crown rot of wheat in Iran. Simple sequence repeats or microsatellite (SSR) and virulence assays were used to investigate genetic variability among 49 isolates of F. culmorum collected from wheat fields in three districts of Varamin. Eight pairs of single-locus microsatellite markers were used to analyze the genomic DNA of isolates. The result of analysis showed that all loci were polymorphic and the numbers of alleles ranged between two to six with an average of 3.75 per locus. Cluster analysis of SSR data revealed that 49 isolates clustered into five distinct groups. The index of multilocus association was calculated using SSR data and 44 multilocus haplotypes were detected among 49 isolates. The results of this study indicated that a there was a high level of genetic diversity (0.528) among the isolates examined, and genetic similarity among Varamin isolates was less than those obtained from Pishva and Javad-abad regions. In addition, pathogenicity of the isolates was tested on a bread wheat cv. Bolani under greenhouse conditions. A significant difference for pathogenicity was found among the isolates. Comparison of the means showed that the isolates of Varamin districts were more pathogenic than Javad-abad and Pishva districts. The significant difference in the genetic diversity and pathogenicity of the Varamin’s isolates in comparison to the other districts suggests that there is a potential for the occurrence of new genotypes with greater virulence in this district. The statistically no correlation was observed between molecular variation and pathogenicity.

Four species of fruit flies (Dip.: Tephritidae), Acanthiophilus helianthi (Rossi), Chaetorellia carthami Stackelberg, Terellia luteola (Wiedemann), Urophora mauritanica Macquart, and the safflower gall wasp, Isocolus tinctorius Melika & Gharali (Hym.: Cynipidae) are serious pests of safflower fields in Iran. Twelve species of hymenopterous parasitoids of these pests were reared and some of their morphological and biological data were presented. These parasitoids belong to the families Eulophidae, Eurytomidae, Ormyridae, Pteromalidae, Torymidae (Hym.: Chalcidoidea) and Braconidae. Two species, Pronotalia carlinarum (Szelényi & Erdös) (Eulophidae) and Pteromalus albipennis Walker (Pteromalidae) are recorded for the first time from Iran. Association of Bracon luteator Spinola, Colotrechnus viridis (Masi), Microdontomerus annulatus (Boucek), Pronotalia carlinarum, and Pteromalus albipennis with safflower fruit flies, and the association of Ormyrus gratiusus (Förster) (Hym.: Ormyridae) with the safflower cynipid gall wasp are newly recorded. An illustrated key is provided for the adult parasitoids.